this is "world news tonight." the navy s.e.a.l. targeted known as america's deadliest sniper. he was a champion of returning veterans. gunned down bay fellow vet. tonight the suspect, the investigation and martha rad at standing by. is it america's invisible epidemic? a 5-year-old being held hostage in a bunker. what the suspect now wants and what we're learning about the boy's condition. the scare outside the palace. a terrifying scene in london at buckingham palace. the man with knives, the police who had to act fast.

the super bowl's superstar. which celebrity will win off the field? and will anyone be able to tackle betty white's moment. >> you're playing like betty white out there. >> that's not what your girlfriend says. >> baby! from abc news world headquarters, this is abc world news with david muir. good evening. thank you for being here on this sunday night. we begin this evening with that unfolding tragedy a former navy s.e.a.l., a hero to members of the military. this evening authorities say he was targeted and killed by a fellow veteran. he took out more enemies than anyone else did as a sniper. he often said he preferred to think about the lives he saved doing it. he returned to help american troops recover from the invisible wounds of war. tonight this young man, eddie routh, is accused of killing him. ryan owens leads us off tonight.

>> reporter: former navy s.e.a.l. sniper chris kyle was such a good shot he once hit a target more than a mile away, but police say it was a bullet fired at point blank range that ended the life of the husband and father of two. >> i'm a better husband and father than i was a killer. >> reporter: the 38-year-old died at a place he should have felt comfort anl, this gun range southwest of dallas. and detectives say he died at the hands of a young man he was trying to counsel. >> the suspect's mother, she may have reached out to mr. kyle to try and help her son, and we kind of have an idea that maybe that's why they were at the range for some type of therapy. >> reporter: officers arrested this 25-year-old former marine, eddie ray routh, after a police chase saturday night. they sd that routh turned the gun on kyle and a friend, chad littlefield, murdering them both. his family told them he was having trouble readjusting to life at home after years of war. that's something kyle spoke about frequently.

>> you don't have an identity. you have to learn a whole new way to act. >> reporter: he volunteered to help vets suffering from ptsd. he knew the stress of combat as well as anyone. he served four deployments, won seven medals of bravery and killed more than 150 people. he was the deadliest sniper in u.s. military history. >> i loved the job, the guys, the camaraderie. it came down to where i had to choose them or my wife and kids. i couldn't have both any more because i'd already messed that up. so i chose the family. >> reporter: on the home front kyle became a best selling author. in his autobiography "american sniper" he writes of shooting so many iraqi insurgents they nicknamed him the devil. to survive all of that to be killed only here at home. tonight that young marine faces two counts of capital murder, one for each of the men who was trying to help him heal.

navy s.e.a.l. chris kyle often said himself how difficult it was for troops to return from war. from serving the greater good, he said, overseas, to serving their own good once home. and this number tonight, nearly 20% of returning troops suffer from symptoms of post-traumatic stress. and they're the ones we know about. martha raddatz in the middle east tonight reporting on what might be an invisible epidemic. >> reporter: for our veterans, for anyone suffering post-traumatic stress, it is a feeling of powerlessness, numbness, your mind frozen in battles long ago. >> i couldn't stop thinking about iraq. >> i didn't care any more. >> i felt empty. i was just a shell walking. >> reporter: former marine brendan schnitzel is one of 70,000 service members in the last decade who have been diagnosed with post-traumatic stress disorder. 70,000. with it can come depression, substance abuse, anger

management, suicide. >> i was constantly feeling anxious. i constantly felt like something bad was going to happen. >> reporter: it is too early to tell whether ptsd or mental health issues contributed to today's horrific murders but it has happened before. in 2007 a mentally unstable army sergeant went on a killing rampage in a combat stress facility at his base in iraq. and retired staff sergeant robert miltonberger who received a silver star for saving countless lives in a hellish 2004 battle in iraq was later diagnosed with ptsd. he says he now avoids firearms, fearing he could hurt someone. >> if i had a gun and someone would threaten me, i could pick me me shooting him and i can see the bullet going in him and the bullet coming out and all of that. >> reporter: ptsd is not new, but with tens of thousands now coming home, the fear is that we still don't know enough about it. >> we are in the dark in our

ability to treat post-traumatic stress to a level that we can guarantee most individuals who have it can recover from it. >> martha joins us now where she's spent the decades covering the wars. chris kyle known for his outreach, helping soldiers traumatized by war, you wonder if he couldn't get through, what do we need to be doing as a nation? >> i think what we have to do is exactly what chris kyle wanted to do. there has to be some sort of outreach to america's veterans. we have to figure out what the problem is. some of the people in that piece, two of the young men, have been in therapy, intense therapy. they've turned their lives around. so it can work, it does work. we can't look at our veterans as victims. we can't look at them all as crazy. therapy does work. we just have to figure out what kind of therapy and take care of

them when they do come home. >> all right, martha, i know you'll stay on this in the coming days and weeks. our thanks to you tonight. we do move to alabama where it is day six of the hostage drama, that 5-year-old boy being held in an underground bunker. tonight we learn what his captor is asking for and about the boy's condition, why his mother is so worried. gio benitez in alabama again tonight. >> reporter: an alabama community shaken by a standoff now in its sixth day came together to mourn 66-year-old school bus driver chuck poland. >> mr. poland was a gentle and kind man. >> reporter: letters from children read aloud. jimmy lee dykes got on to the school bus demanding two children, shot and killed poland, then kidnapped a 5-year-old named ethan, holding him hostage in his home-made underground bunker. >> he's watching over ethan.

>> reporter: also watching overnight drones, we spotted them this morning flying over the bunker site. we're told dykes has demanded that a reporter be sent down into the bunker to speak with him. the fbi tells us, quote, mr. dykes continues to make the childs a comfortable as possible. even so, people close to the child's family say ethan's mom is devastated and worried because ethan has a form of autism. >> he has behavior problem, and she doesn't want him to get into one of those moods where he's uncontrollable. >> reporter: as we told you last night, ethan's birthday is this week. he turns 6. so he could spend it as a hostage, david. >> gio benitez this evening. thank you to you. a man wielding knives held police at bay all while tourists watched. >> reporter: chaos erupted as crowds were watching the famous

changing of the guard at buckingham palace. a man rushed forward brandishing knives holding one to his neck. police moved in taking him down with a taser. bystanders were stunned by how quickly it unfolded. >> he fell on the ground in a couple of seconds. >> reporter: tourists captured the drama on their cameras and phones, posting the videos on youtube. the man is believed to be in his 50s. we're told the queen wasn't home at the time. in the end, nobody was seriously injured. david. >> still some terrifying pictures going viral. thank you. tonight from turkey, new clues into the death of that american mother on a trip texting her husband and children photos. her last text saying she'd be home the next day. last night here we told but the grew 134 discovery. tonight with more on the investigation from turkey. >> reporter: 33 srld sarai sierra is dead.

today plainclothes detectives scoured for clues. she suffered from a blow to the head. but they don't know who killed her or why. >> her body was found in those trees behind me. you can see the police are still here. this is a pretty isolated area. on this side there's a drop-off, on this side a train track. the theory is she was killed somewhere else an her body brought here. >> reporter: police are combing through hundreds of hours of surveillance video. this is the last time she was seen walking through a mall one day before she was due home. >> she stayed in this basement apartment, a mostly working class neighborhood. one of the intriguing mysteries to this case is why would she leave her cell phone, medical records, even her passport behind in her room. >> reporter: police say she didn't get caught up in drugs or trafficking and are questioning at least 11 suspects. sarai exchanged e-mails with one of those suspects the day she vanished but he's been released. so police along with the fbi continue to comb through every clue in a case that very much is

still open. david? >> nick schiff rin reporting in again from turkey tonight, thank you. back here at home in what's become a tradition for the president, an interview on super bowl sunday knowing millions will be in front of their tv for the big game. he took on two flash points. rita, the first one involved the boy scouts? >> reporter: that's right, david. this week the leader of the boy scouts of america will meet to decide whether to lift the ban on gay scouts and leaders. the president said it should be. >> my attitude is that gays and lesbians should have access and opportunity the same way everybody else does, in every institution and walk of life. >> he also took on football on this super bowl sunday, in particular concussion concerns? >> that's right. you know, he applauded the nfl for doing more on concussions. but here's what he had to say when he was asked about having his own child play football. >> i'd have to think about it. it's hard to say no to a kid

when they have a passion for something. i have daughters. they don't have a passion for football. it is a great sport. i am a huge fan, but there's no doubt that some of the concerns that we've learned about when it comes to concussions have to give parents pause. >> david, he said the nfl is different, that these men, they get paid very well, but that children really need protection against the dangers on the field. >> thank you. as you know, we'll have much more on concussions. our own investigation coming up later here in the broadcast. but first, the super bowl itself. you can imagine being those parents tonight of those two brothers who take to the field who will be competing against one another as coaches. the parents already talking about the son who will lose. josh elliott in new orleans tonight. >> reporter: as brothers and rivals, jim and john harbaugh will work opposite sides of the field tonight while somewhere in the super bowl stands a mother

and father quietly root for both teams. jackie and jack harbaugh have spent a lifetime guiding their boys to this history making moment. still just last week mom joked that she was hoping for a tie. >> well, i think that the nfl changed that rule. i think if it ends in a tie, it will be a tie. >> reporter: but they know only one team can win, and so only one of their sons can be the winning coach, and at the end of the night, brother will still face brother. >> i've given absolutely no consideration to the post game handshake or bear hug or anything else. have not thought about that for one second, jerry. have you, jim? >> i have not. >> reporter: but mom and dad have thought about it quite a bit. >> i'm going to hug both of them. >> my thoughts go to that one that will not experience the thrill of victory, and that's where our thoughts will be. >> reporter: josh elliott, abc news, new orleans. >> josh will be there first

thing in the morning with reaction on "good morning america." ahead, getting parents answers for those concussions the president was talking about. what was change katie on this label after abc news started asking questions. predicting who will score during the commercials. and will anyone ever be able to tackle betty white's starring role? we'll be back. we're all having such a great year in the gulf, we've decided to put aside our rivalry. 'cause all our states are great. and now is when the gulf gets even better. the beaches and waters couldn't be more beautiful. take a boat ride or just lay in the sun. enjoy the wildlife and natural beauty. and don't forget our amazing seafood. so come to the gulf, you'll have a great time. especially in alabama. you mean mississippi. that's florida. say louisiana or there's no dessert. brought to you by bp and all of us who call the gulf home.

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we're going to turn to an abc news investigation on this super bowl sunday so many parents with their own children who are aspiring football stars, but there is growing concern about concussions on the field and their long-term damage. tonight terry moran on one company's product. can it protect against concussions? >> reporter: jennifer brannen is like a lot of moms whose sons play football. she worries about head injuries but supports tyler, her boy. >> as mom, you may want to put bubble wrap around him and protect him forever, but that's not going to happen. >> reporter: now a burgeoning cottage industry has emerged selling products to parents and players who are worried about the risk of football concussions. one company, on equal technologies, has riz on the the fore with nfl endorsements -- >> i don't feel like i'm taking a risk. >> reporter: and three blunt words on the box, concussion

reduction technology. he's the founder and ceo. >> these athletes need to take control of their own safety. >> reporter: his products include bulletproof kevlar that you glue into the helmet. but some experts are skeptical. the guy would have you believe it's his magical material. there's nothing magical about it. >> reporter: dave halstead is technical director at the southern impact research center, one of the leading testing labs for sports equipment in the nation. here's the problem -- the modern football helmet already offers excellent protection against direct hits, which produce sharp linear forces against the skull. halstead says testing shows the unequal strips show it can reduce the severity from certain angles like the front but not from other angles. and doctors believe many football concussions today are caused by shearing rotational forces when the head snaps back and swerves around on the neck and the brain slams against the inside of the skull.

there is no proof that products like unequal technology's strips protects against those injure, the ones suspected of frequently causing concussions. so you say concussion reduction technology. is that what you're doing? >> our claim is that we help reduce the possibility of head injury. that's our claim. we never mention the word "concussion". >> reporter: concussion reduction technology. >> exactly. that's the name of the product. >> reporter: but you're claiming that it reduces concussions or that's the name of your product? >> mm-hmm. we're not claiming that. >> reporter: even though your product is called concussion reduction technology. >> correct. but we're not claiming that. one is a name and one is a claim. and our claim is that we help reduce the possibility of head injury. >> reporter: after that interview, the company changed its packaging, actually removing the words "concussion reduction technology" from the box. david, it's now just called crt.

>> they changed the labeling after your "nightline" investigation. but this is a real concern for parents. it would seem that products like these play into the fierce of parents who just really want to make their kids safe. >> absolutely. parents need to read the fine print on these products, see what they're actually claiming. learn about concussions to see what science understands about them. and most important advocate for rules changes that will keep our kids safer. >> you've been looking into all these products and there is no magic bullet. >> there is no magic bullet for this problem. when we come back, not just the super bowl tonight. there's the other one unfolding this sunday, the puppy bowl. take a guess, how many people do you think watched this? something unexpectedhe dos and you see the woman you fell in love with. she's everything to you. but your erectile dysfunction - that could be a question of blood flow. cialis tadalafil for daily use helps you be ready anytime the moment's right. you can be more confident in your ability to be ready. and the same cialis is the only daily ed tablet approved to treat ed and symptoms of bph,

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we're going to turn now to our instant index on a sunday night. from the super bowl to the supercute. the puppy bowl, this is the ninth time they've done this, featuring rescue and shelter puppies. half time show feature not the puppies but some kittens. believe it or not, 111 million people tuned in to the super bowl last year, 9 million actually tuned in to the puppy bowl. we were impressed by that. the other competitors tonight, samsung trying to make a play. this new ad during the game tonight, samsung spending $15 million for a two-minute commercial. paul rud and seth rogen getting together to tape the commercial for the next big thing. >> they gave me a phone. they gave it to me because i'm

the next big thing. this makes no sense, man. >> are you sure that maybe you're not here to see a guy named sam sung? >> we want to know which ad is your favorite tonight. you can let me know. i'm @davidmuir on twitter. she staged a comeback all because of her super bowl moment. she's golden. s. you wouldn't want your doctor doing your job, the pitch! whoa! so why are you doing his? only your doctor can determine if your persistent heartburn is actually something more serious like acid reflux disease. over time, stomach acid can damage the lining of your esophagus. for many, prescription nexium not only provides 24-hour heartburn relief, but can also help heal acid-related erosions in the lining of your esophagus. there is risk of bone fracture and low magnesium levels. side effects may include headache, abdominal pain and diarrhea. call your doctor right away if you have persistent diarrhea. other serious stomach conditions may exist. don't take nexium if you take clopidogrel. let your doctor do his job. and you do yours. ask if nexium is right for you.

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and finally tonight here, the superstars of the super bowl. not the once on the field, the ones off it. the celebrities who pop up with the ads. many have made their mark in ta moment, others have made a comeback. >> reporter: they're the celebrities stealing the show off the field. those super bowl ads have a way of launching careers and reviving others. >> you're playing like betty white out there. >> that's not what your girlfriend said. >> reporter: betty white with this ad for her comeback. last year's seeing ferris bueller all grown up. >> he bought it. >> reporter: and who could forget this cindy crawford classic? the supermodel at the height of her fame in 1992 admired for her pepsi can?

>> is that a great new pepsi can or what? >> reporter: this year swimsuit model kate upton promises to heat things up. for about $4 million a spot, if they're not sexy, they better be funny. >> i got a new boat! >> reporter: one thing's for sure, there's always a breakout star. so who will steal this year's show? maybe the rock. >> got to go to work. >> reporter: or perhaps psy. ♪ >> reporter: but most of the time the best once are a surprise. >> you want the bears and i want the colts but we both win because we're in love. >> honey, don't talk with your mouth full. >> i'm sorry. >> still pretty hard to beat betty white a couple of years back. "good morning america" first thing in the morning and diane sawyer right back here tomorrow night. thanks for watching even on super bowl sunday. good night.